The American Council for an Energy-Efficient Economy's 10th annual "Greenest Cars" list includes only vehicles from Asian manufacturers. "When you look at the specs that matter, it's fair to say the imports have Detroit's number," said ACEEE analyst James Kliesch.

By Peter Valdes-Dapena, CNNMoney.com staff writer

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Honda Civic Hybrid

Engine: 1.3-liter four-cylinder

Transmission: Continuously variable automatic

Fuel: Gasoline

City mpg: 49

Highway mpg: 51

Green score: 53

Few visual cues distinguish a hybrid Civic from a non-hybrid one. Besides "Hybrid" badging, the Civic Hybrid has a small aerodynamic wing on the trunk lid and distinctive wheels.

ACEEE's "Green Score" is based on tailpipe emissions as well as pollution created in manufacturing the vehicle. Pollution from manufacturing is estimated based on the vehicle's weight. The average vehicle's "Green Score" is 30.

Disposal of hybrid batteries does not pose an environmental issue, said James Kliesch. Research Associate for ACEEE.

"It's generally agreed that batteres in [non plug-in] hybrids are going to last the life of the vehicle," he said

When the vehicle is eventually disposed of, the battery will almost certainly be recycled because of the high value of the nickel it contains, he said.